Many companies customize the mail template to support specific needs. We even have an OpenNTF project that implements a lot of great ideas on top of the standard mail template. Each time IBM makes a new release of their mail template it creates huge logistics issues for these companies to integrate the customizations with the new mail template.
I would like to see IBM embrace customer customization of the mail template by providing a range of hooks that would make it easier to customize the template without rewriting the existing code. Examples would be for the mail forms to include a "Customize" subform. The subform would be empty when distributed by IBM but could be modified by each site. An empty "Customize" LotusScript library could be included in the code. This LotusScript library could have custom classes that extend the base mail classes used in the template but not have any methods or properties. These could be added by each site, including event processing for events such as PostOpen QuerySave etc.
If this was done a high propertion of customziation could be written in these "Customize" design elemenst and the rest of the mail template could be left untouched.